On June 20th, 1880, was admitted at the "Hôpital de la Charité" in Paris, a 21 years-old man showing a very severe atrophy of most of his muscles. This case was going to mark the history of the neuromuscular diseases. In the present article are presented the main clinical, genetic, electrophysiological and anatomical data of this patient. It was tried to reconstitute how they were presented to Landouzy and Dejerine, who found in these data some of the features previously reported by Duchenne, de Boulogne, in 1852 as "atrophie musculaire progressive", and considered after the first post-mortem examination by Cruveilhier (1853) as being of neurogenic origin. In opposition with this theory, Landouzy and Dejerine proposed to refer to their case as "myopathie atrophique progressive", emphasizing thus the concept of "myopathy without neuropathy". The criteria proposed for the recognition of the new entity were perfectly described in their two memoirs (1885 and 1886). The characters of facial involvement, the occasional early onset, the selective and often asymmetrical weakness and atrophy of the limb muscles, the variability in severity from one member to another in the same family, were clearly showed. Furthermore, two cases reported in the 1886 memoir presented some involvement of the facial muscles which was demonstrated only by histological examination. The present article evokes the polemical discussion about the relationship of the "myopathie atrophique progressive" with the juvenile form of muscle dystrophy described by Erb at the same time, but without any anatomical or histological data. It is indicated also how the different views about the "scapulo-humeral" forms led to some metamorphosis of the "myopathie atrophique progressive" in "facio-scapulo-humeral dystrophy" in further classifications. This article is illustrated with micrographs taken from the original sections of Dejerine, which could be traced up to now and probably are reproduced photographically here for the first time.